Draft Beer Foaming Problems: Common Causes and Solutions.

So you made the right decision and started buying full kegs for your home, or have thrown out all your bottles and now only keg your homebrew.  But now when you go to pour the perfect pint, you are left holding a glass with a few tablespoons full of beer covered by 15 ounces of head.  Not very impressive, but don’t worry because solving your foaming problems can be very straightforward.  Below we will discuss the many cuases of foaming beer and offer some solutions.

Carbon Dioxide Behavior

Carbon Dioxide (CO2) is responsible for the wonderful mouth feel, the beautiful head that tickles your nose, and the sparkling bubbles that gracefully rise to the top of your pint.  But it is also a very capricious part of your beer that if not handled correctly will be responsible for turning a perfect pint into a glass of “gas”.  It is important to remember a few simple concepts of gas law:

  • The colder your beer is stored, the more CO2 you can dissolve in it.  Conversely, the warmer your beer is the less CO2 that will remain in solution.  Keep your lagers between 35-40, and your ales below 55 degrees.
  • The more pressure you put on the beer (higher regulator pressure), the more CO2 you can force into solution.  The more CO2 in solution, and the easier it will be to do something that will cause it to be released (foam).
  • The smoother the trip through the lines and into the glass the less CO2 that will be released from the beer.  If the beer lines are rough, or the beer glass is not perfectly clean the more nucleation sites available for bubbles to form and cause foaming.
  • Physical agitation will release CO2 from solution; to test this shake a beer can and open it (or better yet, have a friend open it far away from you).

The right level of carbonation

How much CO2 should be dissolved in beer depends on the beer style and the personal preferences of the beer drinkers.  Here are the most common carbonation levels for various beers; you can adjust these to suit your tastes:

  • British Ales- 1.8 to 2.2 volumes of CO2
  • German Lagers- 2.5 volumes
  • American Lagers and Ale- 2.6 to 2.8 volumes
  • Wheat Beers- 3.0 volumes

In order to acheive these levels, use this chart to calculate the correct psi to apply to your keg for force carbonating.

Common problems and solutions

  • Beer comes out flat with no head.  If you are force carbonating your keg and it has only been a few days, try shaking the keg up for 3 minutes and then letting it rest for a few more days.  If you still have no bubbles, check all fittings and junctions in the gas lines for leaks with a soapy water solution.
  • Beer comes out too fast, shooting foam all over.  First check the regulator and set it between 10-15 psi.  If it still blows foam and you have just moved the keg it may need to settle, let it rest for a day or two.  Also, if it has just warmed up recently it will need to sit and acclimate to its new temperature.
  • Your beer pours fine for a while but as the night goes on more foam comes out.  Do you use your fridge for more than just the keg?  If you are opening the refrigerator to get other beverages or anything out, you will be warming up the keg which will drive CO2 out and cause foaming.  The best solution is to use your keg fridge for draft beer only, get another one for wine coolers.  If this is not an option, you can build a secondary “cooler” out of styrofoam insulation that slides around your keg and helps keep the cold air around it while the fridge is open.

If you are having trouble pinpointing the problem, it may be time for new beer lines.  Your lines should be soaked in chlorinate alkaline cleanser in between each keg, then rinsed with baking soda and water.  This will help remove beer stone deposits that can increase foaming, but sometimes new lines are needed.  Try using special beer lines available from many online draft equipment vendors, these are extra smooth and “slippery” to avoid buildup and foam.

Also, really look at the beer as it pours.  If it is foaming in the beer lines as you pour, odds are the dispense pressure is too high.  Even if your regulator says 12 psi, don’t assume the CO2 gauge is correct try turning it back.  We have seen pressure gauges off by as much as 5 psi.  If the beer is traveling up the hose fine but turns to foam as it leaves the tap, try getting larger beer lines as the change in pressure at the end may be allowing CO2 to disperse.

Just remember the keys:  Properly carbonated beer, good clean beer lines, stable storage temperature for the keg, appropriate dispensing pressure, and immaculately clean glasses.  You will soon be on your way to the perfect pint, or two.